This is a project to compare brain self-stimulation and drug self-injection. There are interesting similarities between stimulation of the lateral hypothalamus and injection of drugs of abuse. Both stimulation and injection are highly reinforcing, both can reinforce behavior to the exclusion of natural reinforcers such as food to the detriment of the animal, both have aversive as well as rewarding properties, and both may involve catecholamine psychopharmacology. It may be that both have brain reinforcement mechanisms in common. If so, lateral hypothalamic self-stimulation and stimulation-escape may provide a model for self-administration of drugs and drug abuse. There are important differences between various brain sites for self-stimulation. Drugs of abuse also differ markedly. We will narrow this initial investigation to studies of amphetamine and morphine and lateral and posterior hypothalamic stimulation. A three-way approach has been designed to compare and contrast hypothalamic reinforcement and drug reinforcement. First, in order to match stimulation and drug tests, the standard iv. drug self-injection procedure will be modified to include drug-escape measurements, like stimulation-escape; standard self-stimulation procedures will be modified to include self-titration of current like self-titration of drugs. Second, mutual interaction of hypothalamic stimulation, amphetamine and morphine will be assessed to reveal any overall pattern of effects on positive or negative reinforcement. Third, we will test the possibility that self-stimulation can substitute for self-injection during drug maintenance or drug withdrawl. The significance of this work lies in comparison and extension of self-injection and self-stimulation as animal models of human drug abuse.